His father, Suzaku, was a necromancer and the one responsible for causing the tragedy at the Garan house, which killed Senshirou Furuori's grandfather and a number of other Giou clan members, as he was the one to summon Cadenza.

Although Masamune lived together with Kuroto and Senshirou in Kamakura, they never took it out against him nor did they even mention it in front of him.

After the tragedy, Masamune's family was expelled from the Clan, leaving his mother, Kayako, to take care of him and his younger brother on her own. She apparently overworked herself and broke down, making her last resort to throw out her children and have them beg the Giou Clan for help.

Masamune ended up doing this as was taking in by Takashiro, who offered him the chance to become a necromancer. If he was willing to do so then Takashiro promised to protect him and his family. Masamune agreed to this.